Dredge



F. G. NIELSEN June 2, 1953 DREDGE 2 Sheets-Sheet 1 Filed Aug. 7, 1947 INVENTOR. "of

F.. G. NIELSEN June 2, 1953 DREDGE 2 Sheets-Sheet 2 Filed Aug. '7, 1947 IN V EN TOR. fizcijoffif ielsem BY aw. zdfluwa y Patented June 2, 1953 UNITED STATES PATENT",

OFFICE DREDGE Fridtjof o. Nielsen, Chicago, Ill. M mics-tion August 7-, 1947, Serial No. 767,109

6 Claims. I

This invention relates to a novel dipper dredge and more particularly to a dredge of this type having an improved boom construction.

In dipper dredges of the conventional type, the effective digging force developed by the main hoist cable aflixed to the'dipper is always relatively small because of the sharp angle between the main hoist cable and the dipper handle. This condition is aggravated as increased digging depths are encountered, resulting in a practical maximum boom length. In fact, at increased digging depths with conventional dipper dredges, it has been found that only a small fraction of the main hoist cable pull can-be con verted into useful digging force at the dipper.

The general object of the present invention is to provide an improved dredge and boom construction which overcomes the above objection to a major extent and results in a dredge that will dig effectively at greater depths and will digmore efficiently at a given depth than the prior art clipper dredges.

Another object of the present invention is to provide, in a dipper dredge, an improved boom construction which results in an increased eifective angle between the dipper handle and the main hoist cable.

A further object of the invention is to provide, in a dipper dredge, a movable boom point, the movement of which can be synchronized with the main hoist rope pull to obtain increased digging efiectiveness.

An additional object of the invention is to provide a dipper dredge construction in which the boom and hoisting machinery are positioned on the hull in counterbalancing relationship whereby to counteract. the tipping moment created by the load acting on the boom point and whereby the center ofgravity of all loads acting on the hull lies between the spuds.

Still another object of the invention is to provide a dipper dredge wherein the bow end of the hull, which supports the boom and hoisting machinery, is sufficiently buoyant to support substantially the total weight of the boom and its load, as well as the hoisting machinery, With out the necessity of resorting to complicated trusses in the hull for resisting the bending stresses acting on the hull.

Many of the features shown herein are apt plicable equally to excavating machines whether they be for use on land or on Water, and the term dredge as used herein is to be construed in a sense broad enough to embrace both types of excavators.

Broadly, the dipper dredge of the present in vent-ion comprises a hull having a boom, prefe erably of triangular shape, pivotallyor rockably mounted intermediate its ends on a rotary sup: porting frame which is in turn mounted on the hull. The pivotal or rockable' mounting of the boom permits raising and lowering of the for ward end of the boom or boom point which carries the lead sheave for the main hoist cable. Thus, in each digging cycle, the boom point may be lowered and raised in cooperation with the pull of the main hoist cable acting on the dip-l: per. The lowering and hoisting of the boom point may be manually or automatically syn-... chronized with the main hoist machinery op! erating the dipper, so that the dipper and boom point reach their lowest positions approximately simultaneously in each digging cycle. Sims ilarly, the operation of the boom hoist mas chinery and main hoist machinery may be correlated so that the top or raised positions of the boom point and the dipper are reached approxi-. mately simultaneously.

By thus providing a movable boom point carrying the lead sheave for the main hoist cable, I am able to increase substantially the effective angle between the dipper handle and the main hoist cable when the dipper is in digging position. An analysis of the forces involved will show that for the same main hoist rope pull, the dipper handle compression component is less and the digging force component acting on the dipper is greater in my construction than in the prior art dipper dredges in which the boom point remains in fixed position during the digging cycle or in which the lead sheave for the main hoist cable is not carried by the boom point.

I am able to achieve further advantages in the dredge construction of the present inven. tion by locating the various hoisting units either on the boom or on the rotary supporting frame in counterbalancing relationship. For example, by leading the main hoist cable from the dip.

per upwardly over the boom. point and thence rearwardly to the tail of the boom and d-DWIla wardly to the main hoist, machinery mounted which counteracts at least a portion of the or. posite tipping moment caused by the load act-.-

ing under the boom point. Obviously, this arrangement reduces the net work required to lift the boom point and likewise reduces the load on the boom hoist machinery. Further reductions in the work required to raise the boom point are accomplished by positioning the boom hoist machinery and the dipper handle thrust machinery on the boom and rearwardly of its pivotal mounting point. A further advantage that follows from the counterbalancing relationships of the present dredge construction is that the ultimate load or center of gravity of all loads acting on the hull falls within the perimeter of the rotary frame and consequently within the area between the side spuds carried on opposite sides of the hull. Thus, there is no tendency toward lifting of one of the side spuds when the boom is swung into side position as in side digging or dumping. 1

As will be seen from the detailed description hereinafter provided, the preferred embodiment of the invention comprises a triangular boom pivotally supported at one apex on the rotary supporting frame. The triangular boom is constructed of elongated side members extending forwardly and rearwardly from the lower or sup' porting apex and an elongated top member connecting the outer ends of the two side members to form a forward apex comprising the boom point and a rear apex comprising the tail of the boom. Lead sheaves for the main hoist cable are provided adjacent the forward and rear apexes. Additional structural details of the device will be apparent from the attached drawings and the accompanying description thereof. Although only one specific form of the dredge is shown in the drawings, it is not intended that the invention be limited to the specific structural details shown since it will be obvious. that certain mechanical equivalents may be substituted and other modifications made without departing from the scope of the invention.

. Figure 1 shows the dredge in side elevation with the boom and dipper illustrated in lowered position in solid lines and in raised position in dotted lines. 7

- Figure 2 is a plan view of the dredge showing the general outline of the hull and the rotary frame.

Referring particularly to Fig. 1, the dredge comprises generally an elongated hull 3, a rotary supporting frame 9 mounted on the bow 4 of the hull 3, a triangular boom formed by side members I2 and I3 and top member l4, and pivotally mounted on frame 9 at its lower apex H, a dipper handle i9 carrying a dipper 2i, and the various hoists for operating the main hoist cable, the boom hoist cable, the backing rope, and the dipper handle thrust mechanism.

The hull 3 is provided with a pair of side spud wells 1 and a rear spud well 5 through which elongated spud members 8 and 6, respectively, extend to the bed of the lake or river for anchoring the dredge in place.

Spud machinery of the conventional type may be located in the areaways 38, and power plant hatches are provided at the areaway 39 shown fragmentarily in Fig. 2. Suitable provision may also be made for the location of fuel tanks and ballast tanks in the conventional manner.

. The bow of the hull is constructed in projecting semi-circular form and is peripherally aligned or coextensive with an upper circular supporting frame 9 rotatably mounted thereon by means of a vertical central pintle 4|. The circular frame 9 is rotatably mounted on the bow portion of the hull by means of a plurality of rollers or roller pins In which engage. a set of upper and lower circular rails 43 and M attached to the bottom of the rotary frame 9 and to the deck of the hull, respectively. The bow portion of the hull is preferably constructed so as to provide sufficient buoyancy and displacement to carry the weight of the revolving frame 9 and the units mounted thereon substantially inde pendently of the remainder of the hull. As clescribed hereinafter in greater detail, the various units are mounted on the rotary frame in oounte'rbalancing relationship, whereby to counteract the tipping moment created by the load acting on the outer or forward end of the boom. As a result of this arrangement, the bending moment acting on the hull structure is reduced considerably and the resultant reduction in bending stresses makes it possible to obtain a sufficiently rigid and strong hull without the necessity of resorting to complicated. and high trusses which have previously been considered necessary in the conventional dipper dredges.

A triangular boom is rockably or pivotally mounted at its lower apex on a horizontal axis H on the rotary frame 9 and forwardly of the vertical axis of the pintle 41. The principal structural members of the boom are the side members [2 and 13 extending outwardly or for wardly and inwardly or rearwardly of the lower apex, respectively, and a top member Ill connecting the free ends of the two side members. thereby forming outer or forward apex i5 and inner or'rear apex Hi.

The top and side members of the triangular boom are reinforced by connecting trusses or braces shown at 36. A pair of sheaves H are provided at the forward end of the boom adjacent forward apex I5, and a second pair of sheaves l8 are carried at the rear end of the boom adjacent rear apex [6. The side member 12 of the triangular boom carries an elongated dipper handle 19 which is movable longitudinally by means of a shipper shaft 2!? and which is attached to a dipper or scoop 2| hingedly fixed to the dipper handle at 30. The main hoist cables are connected to the dipper 2! at as and extend upwardly over the sheave I1, thence rearwardly to the sheaves l8, and finally downwardly to the main hoist machinery and winches 22.

It will be understood that the term hoist cable is employed in the specification and claims in its broadest sense and is intended to embrace ropes, steel or wire cable, chains, or any suitable tension member. I

By the above described arrangement of a pivotally or rockably mounted triangular boom, a sub-- stantial operating advantage is achieved in that the pull of the main hoist cable downwardly from the tail of the boom creates a tipping moment which tends to counteract the opposite tipping moment caused by the load acting on the boom point. Obviously, the net result is areduction of the work required to lift the boom point and, consequently, a reduction of the load on the boom hoist machinery. i

Pivotal movement of the boom about the axis i! is effected by means of the boom hoist ma-,

chinery 24. While various types of such .machinery may be used, I show the boom hoist cable 25 extending from said machinery to the.

aec cse the tail of the boomadjacent the apex $6. How ever, in order to counterbalance the weight of the forward end of the boom, I prefer to locate the boom hoist machinery as depicted in the drawings. 1

The dipper handle thrust machinery 21 is mounted on the boom, preferably rearwardly of the lower apex I i as shown in order to obtain ad ditional counterbalancing effect, and is opera,

tively connected by suitable driving means, such as a rope thrust drive 9.8, with the dipper han die 19.

Backward movement of the dipper handle beyond the vertical is accomplished by the back-- ing machinery 35, mounted on the rotary frame 9 to one side of the pintle H, and a backing rope 32 extendingfrom the backing machinery over a guide spool 34 and thence through a set of upper and lower guide sheaves or pulleys $3v to the dipper handle at 3|. Swing machinery iiiis also'provided internally of the rotary frame 8 for effecting rotation of the latter.

In operation, the boom point'is lowered to diggin position as shown in solid lines in Fig. l. The dipper handle [9 is then moved downwardly and pulled rearwardly by backing rope 32 until the dipper 2! is in digging position. The rope thrust drive 28 is then held by means of a braking mechanism (not shown) on the thrust machinery 21 to prevent upwardly shifting movement of the dipper handle It during the digging stroke. The main hoisting machinery then operates the .main hoist cable 28 to move the dipper 2.! forwardly into the earth 31, and shortly after the digging 'movement starts the boom hoisting machinery 2d acting in conjunction with the boom hoist cable 25 draws the rear end of the boom downwardly, thereby liftingtheforward end of the booman'd assisting the main hoist cable or dipper pull in raising the dipper. The lowering and raising of the boom point is preferably synchronized either manually or automatically with the main hoist cable pull so that.

the dipper and the boom point arrive .at their lowest and highest positions approximately simultaneously during the digging cycle. At the upper portion of the diggingstroke, the brake on the thrust machinery 21 is released and the pull of the main hoist cable 23 causes the dipp r handle Hi to be retracted lengthwise to theposition shown in dotted lines in the upper portion of Fig. 1.

As previously described, an important advantage which is achieved by a dredge having the boom construction of the present invention is an increase in. the effective angle between the main hoist cable and the dipper handle. It will be apparent that in a dipper dredge wherein the boom point remains in a fixed upper position during the digging cycle, the angle A, as indicated on Fig. l, is necessarily small when the dipper is in digging position with the result that the dipper handle compression is undesirably high and the digging force available at the dipper is undesirably low. However, the movable boom point construction of the present invention permits the angle A to be increased substantial- 1y, resulting in a marked reduction in the dipper handle compression component and a corresponding increase in the digging force component acting on the dipper.

Another important advantage which follows from the novel dredge construction of the present invention is the combined effects of (a) the counteracting tipping moment created by the main hoist rope pull actingon the rear end of. the boom, and (b) the location of the various machine units in counterbalancing relationship on the rotary frame. As a result of these two effects, the center of gravity of all loads actingon the hull falls well within the perimeter ofthe circular supporting frame over a wide range of digging conditions thereby achieving a high, degree of stability. This result is particularly important with respect to the load imposed on the side spuds. In the conventional type of dredge when the boom is swung sideways with respect to the hull, as in side digging or dumping, it often happens that the resultant force or point of ultimate load falls outside of one or the other of the two side spuds. In other words, the cen--v ter of gravity of all of the loads falls outside of the hull with the result that there is an excessive load on the spud operating ropes on that side and a marked tendency toward lifting of the spud on the opposite side. tion of my invention obviates all such diinculties because the center of gravity of all loads acting on the hull falls within the perimeter of the rotary frame and consequently within the area between the side spuds.

I claim:

1. A digging machine comprising, a supporting frame rotatably mounted on a vertical axis, an elongated boom extending outwardly from said frame and pivotally mounted intermediate its ends on said frame on one side of said vertical axis and within the perimeter of said frame. outer and inner sheaves disposed at the outer and inner ends of said boom, a dipper attached to a dipper handle pivoted on said boom intermediate the boom. pivot point and the outer end of said boom and reciprocable relative to the boom, main hoist machinery mounted on said frame on the opposite side of said vertical axis. a main hoist cable connected to said dipper and extending over said, outer sheave and thence rearwardly over said inner sheave and downwardly to said main hoist machinery, boom hoist machinery mounted on said boom adjacent the inner end thereof, and a boom hoist cable affixed to said frame and extending to said boom hoist machinery.

2. A dredge comprising a hull, a supporting frame rotatably mounted on a vertical axis on said hull, a triangular boom pivotally mounted atone apex on said frame at one side of said vertical axis and extending outwardly from said frame, a dipper attached to a dipper handle carried on said boom intermediate said apex and the outer end of the boom, main. hoist machinery mounted on said frame on the opposite side of said vertical axis, a main hoist cable connected to said dipper and extending over said outer end of said boom and thence rearwardly over the inner end of the boom and downwardly to said main hoist machinery, boom hoist machinery mounted on said boom adjacent said inner end, a boom hoist cable affixed to said frame and extending to said boom hoist machinery, and dipper handle thrust machinery mounted on said boom adjacent said inner end and operatively connected with said dipper handle to move the latter lengthwise with respect to said boom.

3. A dredge comprising a hull, a supporting frame rotatably mounted on a vertical axis on said hull, a triangular boom pivotally mounted -at one apex on said frame on one side of said vertical axis, said boom comprising elongated side members respectively extending outwardly The dredge construc-,

7. and inwardly from said one apex and an elongated top'member connecting the free ends of said side members to form outer and inner apexes, outer and inner sheaves disposed adjacent said outer and inner apexes, a dipper attached to a dipper handle carried on said outwardly extending side member, main hoist machinery mounted on said frame on the opposite side of said vertical axis, a main hoist cable connected to said dipper and extending over said outer sheave and thence rearwardly over said inner sheave to said main hoist'machinery, and boom hoist machinery mounted on said top member adjacent said inner apex, a boom hoist cable affixed to said frame at said opposite side and extending to said boom hoist machinery, and dipper handle thrust machinery carried on said inwardly extending side member and operatively connected with said dipper handle to move the latter lengthwise with respect to said outwardly extending side member.

4. A dredge comprising a hull having a pro jecting semi-circular end portion peripherally aligned with an upper circular supporting frame rotatably mounted on said hull on a vertical cen ter axis coincident with the axis of said end portion, a triangular boom pivotally mounted at one apex on said frame on one side of said axis and within the perimeter of said frame, said boom extending outwardly from said frame, an elongated dipper handle attached to a dipper at its outer end and movably mounted on said boom intermediate said apex and the outer end of said boom, main hoist machinery mounted on said frame on the opposite side of said axis and operatively connected by means of a main hoist cable to said dippenbacking machinery mounted on said frame and operatively connected by means of a backing cable to said dipper handle, boom hoist machinery mounted on said boom adjacent the inner end thereof and operatively connected by means of a boom hoist cable to said frame at said opposite side to effect pivotal movement of said boom about said apex, and dipper handle thrust machinery mounted on said boom and operatively connected to said dipper handle to move the latter lengthwise with respect to said boom.

5. A dredge comprising a hull having a frame rotatably mounted on one end thereof on a vertical axis, a triangular boom pivotally supported at one apex on said frame on a horizontal axis intermediate the ends of the boom within the perimeter of the frame, a dipper having a dipper handle pivoted on the boom intermediate the pivotal support and the outer end thereof and reciprocable relative thereto, a main hoist cable extending from the dipper upwardly over the outer end of the boom thence inwardly over the inner end of the boom and then downwardly, a main hoist mounted on said frame adjacent the inner end of the boom, a boom hoist carried on the inner end of the boom, a boom hoist cable connected to said boom hoist and to said frame, and a pair of spuds carried by the hull on opposite sides of said frame and positioned laterally beyond the point of the ultimate load acting on the hull.

6. A digging machine comprising a support ing frame rotatably mounted on a vertical axis, an elongated boom extending outwardly from said frame and pivotally mounted intermediate its ends on said frame at one side of said vertical axis, a dipper attached to a dipper handle carried on said boom intermediate the boom pivot point and the outer end of said boom, main hoist machinery mounted on said frame at the opposite side of said vertical axis, a main hoist cable connected to said dipper and extending over the outer end of said boom and thence rearwardly over the inner end of the boom and downwardly to said main hoist machinery, boom hoist machinery mounted on said boom adjacent its inner end, a boom hoist cable afiixed to said frame and extending to said boom hoist machinery, and dipper handle thrust machinery mounted on said boom adjacent its inner end and operatively connected with said dipper handle to move the latter lengthwise with respect to said boom.

FRIDTJOF G. NIELSEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 711,806 White Oct. 21, 1902 711,449 Williams Oct. 14, 1902 751,937 Osgood Feb. 9, 1904 868,267 Hetlesaeter Oct. 15,

1,593,261 Holmes July 20, 1926 2,033,883 Davidson et a1. Mar. 10, 1936 2,048,561 Neveling July 21, 1936 2,188,686 Kersting et a1. Jan. 30, 1940 

